The purpose of this invention is to produce seamless, composite belts for improved polishing of semiconductor wafers as a result of the belts lying flat, without cupping up or down, while in contact with a semiconductor wafer.
Chemical mechanical polishing (CMP) of semiconductor wafers is a relatively new technology used in the manufacture of integrated circuits. Conventional CMP technology involves holding a wafer face down in contact with a flat polishing pad mounted on a rotating turntable. This arrangement derived from traditional glass polishing technology. More recently a new type of CMP polishing tool has been invented by Ontrak Systems, later acquired by Lam Research. The new tool, as described in U.S. Pat. No. 5,692,947, uses a linear polishing member comprising a conventional, flat polishing pad adhered to a supporting endless metal belt. Currently there are no one-piece belts available either for use in polishing semiconductor wafers or for use on Lam's tool.
A division of Scapa Group has been developing a seamless, composite belt for use on Lam's proprietary polishing tool. There are many difficulties and constraints involved with developing such a belt that integrally combines sufficient strength and a precision polishing surface and that can be manufactured efficiently and consistently. One unexpected problem in particular was that the prototype belts would not maintain a flat surface, i. e., the edges of the belt would curl up or down in the span between the mounting rollers, which resulted in poor polishing performance because of uneven contact with the surface of the semiconductor wafer. The present invention overcomes this critical problem.